The successful use of dental implants has long been known and is well documented in the field. Despite successful dental implant procedures through the years, the success of the placement of a dental implant is limited by the quality and quantity of existing bone of a given patient. Due to the destructive nature of dentures to the underlying jawbone the amount of bone in many people is very limited for the placement of dental implants.
Furthermore, atrophy of the jawbone can occur when the bone is not subjected to occlusal loads. Therefore, atrophy may occur over time when a tooth is not replaced with a dental implant. As a result, when a person has been partially endentulous for a long period of time, they may suffer from an atrophic alveolar ridge that is not capable of securely supporting a dental implant. The deterioration of the alveolar ridge has severe consequences, including reducing one's ability to masticate and compromising aesthetics.
In this situation, bone grafting has become an essential element for the successful treatment of those who do not have enough bone for dental implants. There are many known methods of bone grafting. As viable methods, blocks of hip bone have been affixed to the jaw and freeze-dried demineralized bone protein has been used as a stimulant to cause the patient's bone cells to become active and lay down new bone onto the existing bone areas and into the new bone graft areas. Through experience and research, it has become evident that, for bone grafting to be successful, it must be given an isolated space to grow, protected from muscular pressure, tissue impingement and forces of mastication. In order to create this space, fabric-like membranes or barriers have been used over a bony defect. Although this barrier creates an isolated space from the invasion of epithelial cells into the bony defect or bone graft area, it does not create a protected space from chewing forces or tissue pressure. It is necessary to protect the growing bone from all aspects of potential harm. Titanium meshes can be used to achieve this space maintenance; however, this technique has draw-backs, as the titanium mesh must be removed in subsequent surgical procedures.
In many instances the space is created and maintained utilizing dental implants and supports including a tenting-type support screw. Often, the head of the tenting-type support screw is placed away from the bone, providing enough space for placement of bone graft material and subsequent bone growth.
Implantable screws such as the tenting-type screw in this case have commonly been made of surgical quality metals, such as stainless steel, and surgical grade titanium and titanium alloys. Other commonly used materials include ceramics and various plastics. However, the use of these materials have many drawbacks. For example, metal screws typically remain in the body unless they are later removed by a separate operation. Further, metal screws can potentially irritate tissue in close proximity to the screw, shed harmful ions into the body, or loosen to the point of injury among other things. Other commonly used materials offer a comparable list of drawbacks.